About the Relay:
Relay is an electrical control device that usually used in automatic control circuit.
The relay in fact is an automatic switch which uses a smaller current to control a larger current.

About the Relay Pins:
Pins 85 & 86 - are used to turn 'on' the relay. You need a positive (+) and negative (-) power source to
turn on the relay.
- Pin 85 - is usually negative (-)
- Pin 86 - is usually positive (+)
Pin 30 - is either a (+) or (-) source that feeds Pin 87 or Pin 87a
Pin 87 - when the relay is 'on': Pin 30 and Pin 87 are connected

Relay Kits Instructions:
RED + connect directly to battery.
WHITE wire to ignition switch power source.
BLACK goes to thermos switch.
BLUE wire goes to the Fans.

What's Note:
The relay is rated for 30A, while the socket 14AWG wires are not big enough for the rated 30/40 amps.
If you are intending to run 30 amps continuously, you could remove the spade contacts from the connector,
carefully open the crimps securing the wire to the contact and recrimp/solder 10 gauge wires to it.
Also, you can use 6.3 mm female connectors to connect directly to the relay pins. The relay should be good for 30 amps.